The research plan proposes the characterization of intracellular mechanisms by which the cloned thrombin receptor mediates multiple cellular activities. Specifically, the candidate will: 1) identify G proteins which mediate thrombin signaling; 2) determine the functional sites for receptor-G protein interaction; and 3) define the cloned thrombin receptor's role in thrombin-induced activation of intracellular kinase cascades. These studies will allow the candidate to develop expertise in methodologies used to interrogate receptor-mediated signal transduction including: receptor expression in somatic cell and oocyte systems; chimeric receptor engineering; G protein binding assays; MAPK, Raf, and Ras activity assays; and the use of dominant negative mutants to explore the function of various signaling elements.